Molecular diffusion is one of the most basic, and at the
same time most fascinating physical phenomena. It plays a
large role in applications related to separations and
alternative energy production. The main focus of our
research is on the following two directions: (i)
understanding diffusion and its relation to structure and
functionality in complex nanostructured materials on all
relevant length scales, including nanoscale, and (ii)
developing optimization pathways for transport in these
materials. In our research we use unique experimental
technique: pulsed field gradient nuclear magnetic resonance
(PFG NMR) at high field (17.6 T) and high gradients (up to
30 T/m). This approach allows monitoring molecular diffusion
on the nanometer and micrometer length scales. It has been
recently introduced by our group here in Gainesville in
collaboration with the National Magnet Lab. Combined
application of this technique and computer simulations
creates new links between the nanosciences and chemical
engineering by allowing direct studies of the relationships
between structure and translational dynamics in complex
systems. A brief description of main research directions of
our group is given below.

Porous membranes fabricated for separations of gas mixtures are usually structurally heterogeneous. In particular, mixed

matrix membranes contain interconnected networks of pores of different sizes, i.e. networks of micropores with pore sizes approaching the sizes of gas molecules and networks of much larger mesopores. Such membranes have great potential for effective separations of small gas molecules such as CO2, CH4, and N2 from methane-rich biogas produced from
biomass processing and flue gas produced by coal-fired power plants. Our research focuses on (i) quantifying different types of gas transport on micrometer and submicrometer length scales in such membranes and related materials, and (ii) establishing a quantitative relationship between these types of transport and macroscopic long-range diffusion and related gas fluxes. This research direction is supported by an NSF CAREER award, CBET.

Transport of CO2 and Other Gases in Confined Room Temperature Ionic Liquids

Molten salts, which are liquid without any water at temperatures around room temperature, are referred to as room temperature ionic liquids (RTILs). Many RTILs show good solubility for CO2 and some other small gases. Confinement of RTILs in mesoporous channels of porous solids is a promising strategy for the development of a very attractive type of media for gas separations. Our research will uncover fundamentals of the relationship between transport and structural properties of confined RTILs on small length scales. It is supported by a collaborative research award from NSF, CBET (collaborators are Prof. E. J. Maginn, and Prof. J. K Shah, University of Notre Dame)

Single-File Diffusion for Alternative Energy and Separations

The phenomenon of single-file diffusion (SFD) occurs when molecules cannot pass one another in narrow channels. This results in a highly correlated, anomalous type of transport. SFD is of great potential interest for applications in separations and catalysis. This research direction focuses on the first-time experimental observation of single-file diffusion in gas mixtures and on obtaining fundamental knowledge of this type of transport on various length scales of molecular displacements. Studies are performed in collaboration with the group of Prof. C. R. Bowers, University of Florida. This work is supported by a research grant from NSF, Chemistry.